CN104597435A - Correction frequency domain compensation and fractional order Fourier transformation based multi-frame coherent TBD method - Google Patents

Abstract

The invention discloses a correction frequency domain compensation and fractional order Fourier transformation based multi-frame coherent TBD method. The correction frequency domain compensation and fractional order Fourier transformation based multi-frame coherent TBD method comprises the steps of searching azimuth units of all frames of data on the basis that a radar receives multi-frame echo data, selecting the same azimuth data from each data frame, conducting zero setting on other data and using data which are not subjected to zero setting as target echo data to be processed; correcting range walking and range bending phenomena within a range frequency domain-slow time domain, enabling the target echo data in each frame to be well corrected to a range unit, conducting phase compensation on the data in the range unit, enabling echo phases to be coherent, finally conducting fractional order Fourier transformation on the data in the range unit, performing constant false-alarm detection processing according to a Fourier transformation result so as to judge whether a target exists or not and completing corresponding detection. By means of the multi-frame coherent TBD method, a maneuvering target can be effectively detected under the situation of low signal-to-noise ratio, and accordingly the effectiveness of the method is verified.

Description

Based on the multiframe coherent TBD method revising frequency domain compensation and Fourier Transform of Fractional Order

Technical field

The invention belongs to multiframe Radar Signal Processing and space maneuver target detection technique field, particularly relating to a kind of multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order.

Background technology

Because the extraterrestrial target of space based radar detection has at a high speed and the high motion of automobile, while extraterrestrial target distant and radar is shorter for the observation time of target, this just makes the echoed signal of target very faint.In addition, due to the high speed of target and the feature of the high motion of automobile, the phenomenon making target echo data there will be range walk and Doppler within the coherent accumulation time to walk about, namely the backward energy of target can be distributed in different range units and doppler cells, with regard to making, this detects that in echo data faint echo signal becomes very difficult.

Method for dim target detection has follows the tracks of front detection method and (TBD) tracking before detecting; before wherein following the tracks of, detection method carries out hard decision with acquisition point mark by the multiframe data received radar; then the flight path of target is obtained according to a mark; but; hard decision causes many useful Weak Informations and loses, thus reduces the detectability of radar to weak target.And tracking can under the prerequisite not changing existing radar system hardware and structure before detecting, adopt the multiframe data that soft decision process radar receives, namely first do not judge whether there is target, but targetpath possible in multiframe data is followed the tracks of simultaneously, and soft judgement is carried out to the authenticity of these flight paths, gradually the false track be made up of noise and clutter etc. is eliminated, and real flight path is remained, when soft judgement exceedes some thresholdings, be judged as finding target.Before detecting, tracking can make full use of the multiframe echo data of target, effectively can improve detection probability.

But interframe data is all carried out non-inherent accumulation to realize by current TBD method, due to the phase information of non-inherent accumulation meeting lose objects, cause accumulation effect than the weak effect of coherent accumulation.

Multiframe coherent TBD method be just propose recently utilize data phase between radar return and carry out the target detection new method of coherent accumulation.Multiframe target echo data, utilizing on the phase information basis between multiframe target echo signal, are carried out coherent accumulation by the method, thus effectively can improve the signal to noise ratio (S/N ratio) of echo data, enable radar target be detected under low signal-to-noise ratio.

Because multiframe coherent TBD method takes full advantage of the phase information between echo, can have higher accumulate augment than existing conventional TBD method, the theoretical research result in addition for this technology is considerably less; So the maneu-vering target detection technology of research under multiframe coherent TBD framework has important theory and actual application value.

Also not yet occur at present utilizing correction frequency domain compensation and Fourier Transform of Fractional Order to the correlative study achievement of the multiframe coherent TBD technology that space maneuver target detects.

Summary of the invention

In order to solve the problem, the object of the present invention is to provide a kind of multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order.

In order to achieve the above object, the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention comprises the following step carried out in order:

1) space based radar is received to the maneuvering target echo data obtained and carry out process of pulse-compression in distance frequency domain-slow time domain, then after distance frequency domain does inverse Fourier transform, obtain the range gate after pulse compression-slow time data;

2) from every frame of above-mentioned echo data after pulse compression, select same orientation to the data of unit, other data are carried out zero setting process simultaneously, and will the data of zero setting do not had to process as target echo data;

3) in step 2) on the data basis that obtains, search in the parameter area of target, calculate the frequency domain compensation item revised according to Search Results, correct back to range walk and the range curvature phenomenon of wave datum with frequency domain compensation item;

4) utilize step 3) in obtain through revising the echo data of frequency-domain correction, compensate the phase differential between data in a range unit, then the data having compensated phase differential are carried out Fourier Transform of Fractional Order, peak records in fractional order territory is got off and gets back to step 3) cycling, until target component has been searched for, and the maximal value of a series of peak value is put in new information matrix;

5) step 2 is repeated) to step 4), until the orientation of total echo data frame to be chosen and to carry out respective handling complete to cell data;

6) maximal value in information matrix is compared, therefrom choose one and be worth most as detection statistic, and carry out CFAR detection in the detecting unit figure be made up of these maximal values.

In step 1) in, described to the method that echo data carries out process of pulse-compression be:

Under space based radar is operated in detection and tracking pattern, the spatial domain of detection is divided into 10 orientation to, utilize frequency matching filtering method to carry out the kth frame after process of pulse-compression to echo data, the maneuvering target echo data form of the n-th localizer unit is:

$s_r(\hat{r},t_m)=A_r^{\′}\sin c\left[\mathrm{\π}\frac{\hat{r}-R\left(t_m\right)}{{\mathrm{\ρ}}_r}\right]\exp (-j\frac{4\mathrm{\π}}{\mathrm{\λ}}{v}_0{t}_m)\exp (-j\frac{2\mathrm{\π}}{\mathrm{\λ}}{a}_0{t}_m^2)---\left(2\right)$

In formula (1) the complex magnitude of echo data, t _m=mT _r+ (k-1) NMT _r+ (n-1) MT _rthe slow time, k=1 ..., K represents a kth scan period, n=1 ..., N be orientation in the n-th spatial domain to unit, m=1 ..., M, t'=t-t _mthe fast time, represent the length of range gate, T _rthe indicating impulse repetition time, wherein M represents the umber of pulse in the Coherent processing time, f _crepresent the carrier frequency of signal, for signal wavelength, B _sfor signal bandwidth, r ₀represent the initial distance of target, v ₀represent the initial velocity of target, a ₀represent the acceleration of target, it is the radial distance between target and radar; Be stored in a matrix by the known radar return data of formula (1), the horizontal ordinate of this matrix is slow time t _m, ordinate is respective distances unit the fast time.

In step 3) in, described in step 2) on the data basis that obtains, search in the parameter area of target, calculate the frequency domain compensation item revised according to Search Results, the method for the range walk and range curvature phenomenon that correct back to wave datum with frequency domain compensation item is:

Search within the scope of target component, target is calculated for different pieces of information frame and the different azimuth respective correction frequency domain compensation item to unit according to the parameter combinations of each target while search, then echo data is done Fourier transform along distance dimension, distance frequency domain-slow time data can be obtained, then the correction frequency domain compensation item calculated is multiplied by this basis, distance frequency domain f and speed, acceleration and the coupling solutions between the slow time can be removed, reach correction distance and walk about and the object of range curvature phenomenon; Carry out inverse Fourier transform along distance frequency domain afterwards and obtain the range gate after range walk and range curvature correction-slow time domain data.

In step 4) in, described utilizes step 3) in obtain through revising the echo data of frequency-domain correction, compensate the phase differential between data in a range unit, then the data having compensated phase differential are carried out Fourier Transform of Fractional Order, peak records in fractional order territory is got off and gets back to step 3) cycling, until target component has been searched for, and the method that the maximal value of a series of peak value is put in new information matrix be:

In step 3) proper phase that basis is brought to unit due to different Frames and orientation between echo data in compensation range unit is poor, the phase place between data is made to meet phase place coherent pulse signalf, then take out the data compensated in a range unit of phase place and carry out Fourier Transform of Fractional Order, after finishing Fourier Transform of Fractional Order, the peak value in fractional order territory is taken out, then step 3 is got back to) recalculate new correction frequency domain compensation item, carry out cycling, until by complete for the range searching of echo data, the maximal value of having searched for the rear peak value obtaining in each fractional order territory is taken out and is put into a new information matrix A successively _{1 × N}in.

In step 6) in, described compares the maximal value in information matrix, therefrom chooses one and is worth most as detection statistic, and the method for carrying out CFAR detection in the detecting unit figure be made up of these maximal values is:

In step 5) after store the maximal value in the fractional order territory of each orientation to unit scan and after process in the information matrix that obtains; the series of values relatively obtained; most value is wherein taken out as detection statistic; then around detection statistic, protected location and reference unit is selected; thus determine adaptive threshold according to the CA-CFAR check processing method in transform domain; by detection statistic whether cross thresholding judge target with or without, complete detection.

Method provided by the invention receives on multiframe echo data basis at radar and searches for unit the orientation of each Frame, thus in each Frame selection Data in Azimuth Direction, and other data are carried out zero setting process, using there is no the data of zero setting as the unified process of target echo data; Then the range walk occurred echo in distance frequency domain-slow time domain and range curvature problem correct accordingly, the target echo data in each frame are made to be corrected to a range unit preferably, then the data in this range unit are carried out phase compensation, make between echo data, to meet phase place coherent pulse signalf, finally Fourier Transform of Fractional Order is carried out to the data in this range unit, CFAR detection process is carried out according to Fourier Transform of Fractional Order result, thus judge target with or without, complete corresponding detection.By experimental result and the multiframe coherent TBD technology converted based on Radon, the multiframe coherent TBD technology converted based on Keystone, the multiframe coherent TBD technology compensated based on conventional shift with compare based on the detection perform of the multiframe coherent TBD technology of dynamic programming, this method effectively can detect space maneuver target under the state of signal-to-noise also lower than said method, thus demonstrates the validity of this method.

Accompanying drawing explanation

Fig. 1 is the multiframe coherent TBD method flow diagram based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention.

Fig. 2 is that the space based radar after separating mediation process of pulse-compression receives data profile.

Fig. 3 is the echo data distribution plan after frequency domain compensation correction distance range walk and range curvature.

Fig. 4 is P _fa=10 ^-4time CFAR detection curve map.

Fig. 5 is P _fa=10 ^-6time CFAR detection curve map.

Embodiment

Below in conjunction with the drawings and specific embodiments, the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention is described in detail.

Set up maneuvering target echo data model:

Under space based radar is operated in detection and tracking pattern, the spatial domain of detection is divided into 10 orientation to, utilize frequency matching filtering method to carry out the kth frame after process of pulse-compression to echo data, the maneuvering target echo data form of the n-th localizer unit is:

$s_r(\hat{r},t_m)=A_r^{\′}\sin c\left[\mathrm{\π}\frac{\hat{r}-R\left(t_m\right)}{{\mathrm{\ρ}}_r}\right]\exp (-j\frac{4\mathrm{\π}}{\mathrm{\λ}}{v}_0{t}_m)\exp (-j\frac{2\mathrm{\π}}{\mathrm{\λ}}{a}_0{t}_m^2)---\left(3\right)$

In formula (1) the complex magnitude of echo data, t _m=mT _r+ (k-1) NMT _r+ (n-1) MT _rthe slow time, k=1 ..., K represents a kth scan period, n=1 ..., N be orientation in the n-th spatial domain to unit, m=1 ..., M, t'=t-t _mthe fast time, represent the length of range gate, T _rthe indicating impulse repetition time, wherein M represents the umber of pulse in the Coherent processing time, f _crepresent the carrier frequency of signal, for signal wavelength, B _sfor signal bandwidth, r ₀represent the initial distance of target, v ₀represent the initial velocity of target, a ₀represent the acceleration of target, it is the radial distance between target and radar.Be stored in a matrix by the known radar return data of formula (1), the horizontal ordinate of this matrix is slow time t _m, ordinate is (respective distances unit of fast time ).

Apply the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention to process multiframe echo data:

Method provided by the invention can make full use of multiframe echo data, the same Data in Azimuth Direction of each frame in echo data is taken out, in order to not add up to other noise datas in coherent accumulation process, other echo data is needed to carry out zero setting process, then the frequency domain compensation item correcting back to ripple range walk and range curvature is accordingly calculated on this basis, then echo data is tieed up to carrying out Fourier transform along distance, obtain distance frequency domain-slow time data, the data obtained are multiplied by frequency domain compensation item respectively, thus in distance frequency domain, echo data is corrected, then frequency domain data of adjusting the distance carries out inverse Fourier transform, thus the time domain data obtained through range walk and range curvature correction, discontinuous in different pieces of information frame and orientation to the phase place in unit due to target in addition, in order to realize correlative accumulation, so need the phase place using target, the phase place of echo data is needed to compensate, thus echo data phase place can be made to meet phase place coherent pulse signalf, finally the data compensated are taken out and then do Fourier Transform of Fractional Order, and carry out CA-CFAR detection by the result of Fourier Transform of Fractional Order.

As shown in Figure 1, the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention comprises the following step carried out in order:

1) space based radar is received to the maneuvering target echo data obtained and carry out process of pulse-compression in distance frequency domain-slow time domain, then after distance frequency domain does inverse Fourier transform, obtain the range gate after pulse compression-slow time data;

The form of multiframe maneuvering target echo data provides in above-mentioned discussion.

2) from every frame of above-mentioned echo data after pulse compression, select same orientation to the data of unit, other data are carried out zero setting process simultaneously, and will the data of zero setting do not had to process as target echo data;

Because target there will not be the problem of walking about to unit across orientation, in order to not accumulate noise data in processing procedure, therefore need the data be not selected to carry out zero setting process, and will the data of zero setting do not had to process as target echo data.

3) in step 2) on the data basis that obtains, search in the parameter area of target, calculate the frequency domain compensation item revised according to Search Results, correct back to range walk and the range curvature phenomenon of wave datum with frequency domain compensation item;

In step 3) in, need to search within the scope of target component, thus correction distance can be calculated according to target component combination and walk about and the correction frequency domain compensation item of range curvature.First target echo data are carried out Fourier transform along fast time domain to obtain:

$\begin{array}{c}S(f,t_m)=A_r\frac{1}{\sqrt{\mathrm{\γ}}}\mathrm{rect}\left(\frac{f}{B_s}\right)\exp [-j\frac{4\mathrm{\πf}}{c}R\left(t_m\right)]\exp [-j\frac{4\mathrm{\π}{f}_c}{c}R\left(t_m\right)]=\\ A_r\frac{1}{\sqrt{\mathrm{\γ}}}\mathrm{rect}\left(\frac{f}{B_s}\right)\exp [-j\frac{4\mathrm{\πf}}{c}{R}_0]\exp [-j\frac{4\mathrm{\πf}}{c}{v}_0{t}_m]\exp [-j\frac{2\mathrm{\πf}}{c}{a}_0{t}_m^2]\exp [-j\frac{4\mathrm{\π}{f}_c}{c}R\left(t_m\right)]\end{array}---\left(2\right)$

Wherein f represents distance frequency domain, as can be seen from formula (2), be coupled because distance frequency domain f creates with the radial distance of target, and radial distance is relevant with acceleration with the speed of target, so can be known by the character of Fourier transform, due to frequency domain middle distance frequency domain f and the amount appearance coupling along with slow time variations, when so target echo signal being transformed in distance-slow time domain, the echo envelope of target just there will be time delay, delay volume and speed, acceleration magnitude is relevant, also just create envelope to move, thus appearance distance is walked about and range curvature phenomenon.If compensated target echo data frequency-region signal at frequency domain, coupling solutions can be removed, can solve range walk and range curvature problem, again be corrected in a range unit by target echo data, now the position of echo envelope is only relevant with the initial distance of target.Therefore definition correction frequency domain compensation item is:

$\mathrm{\ψ}(f,t_m)=\exp \left(j\frac{4\mathrm{\π}}{c}{\mathrm{fvt}}_m\right)\exp \left(j\frac{2\mathrm{\π}}{c}{\mathrm{fat}}_m^2\right)---\left(3\right)$

Data after process of pulse-compression are carried out Fourier transform along distance dimension, then the data in distance frequency domain-slow time domain are obtained, search within the scope of target component afterwards, along with the search to target component scope, can calculate according to formula (3) and walk about and the correction frequency domain compensation item of range curvature for correction distance, when searching speed and the acceleration of target, formula (3) can be written as:

${\mathrm{\ψ}}^{\′}(f,t_m)=\exp \left(j\frac{4\mathrm{\π}}{c}f{v}_0{t}_m\right)\exp \left(j\frac{2\mathrm{\π}}{c}{f{a}_{0}t}_m^2\right)---\left(4\right)$

Distance frequency domain-slow time data is multiplied by corresponding such as formula the correction frequency domain compensation item shown in (4) respectively, thus obtains the echo frequency domain data through range walk and range curvature correction, be shown below:

$S(f,t_m)=A_r\frac{1}{\sqrt{\mathrm{\γ}}}\mathrm{rect}\left(\frac{f}{B_s}\right)\exp [-j\frac{4\mathrm{\πf}}{c}{R}_0]\exp [-j\frac{4\mathrm{\π}{f}_c}{c}R{\left(}_{t_m}]---\left(5\right)$

And then carry out inverse Fourier transform along the column vector in distance frequency domain-slow time domain, thus obtain the range gate-slow time time domain data through range walk and range curvature correction.Namely following formula is obtained:

$s_r(\hat{r},t_m)=A_r^{\′}\sin c\left[\mathrm{\π}\frac{\hat{r}-R_0}{{\mathrm{\ρ}}_r}\right]\exp (-j\frac{4\mathrm{\π}}{\mathrm{\λ}}{v}_0{t}_m)\exp (-j\frac{2\mathrm{\π}}{\mathrm{\λ}}{a}_0{t}_m^2)---\left(6\right)$

Now the position of target echo data is only relevant with initial distance, and has nothing to do with the slow time, thus has calibrated range walk and range curvature phenomenon.

4) utilize step 3) in obtain through revising the echo data of frequency-domain correction, compensate the phase differential between data in a range unit, then the data having compensated phase differential are carried out Fourier Transform of Fractional Order, peak records in fractional order territory is got off and gets back to step 3) cycling, until target component has been searched for, and the maximal value of a series of peak value is put in new information matrix;

In step 4) in, what suppose taking-up is that first orientation of the first Frame is to cell data (now first thinking target in first orientation in unit), still take out the data of first orientation to unit to the 4th Frame in addition, now the 4th Frame first orientation to the phase place of cell data is:

Wherein in order to make the phase place of echo data be continuous print in time, namely meeting is phase place coherent in time:

Therefore in order to obtain formula (8), need on formula (7) basis superior with following formula:

Then by above-mentioned compensation of phase method, the orientation of each Frame is all compensated to the echo data phase differential in unit according to the target component of each search, make the phase place of all echo datas be all continuous print in time.After phase compensation process, K blocks of data is made to be phase place coherent in phase place, then the data in this range unit are taken out and do Fourier Transform of Fractional Order, and the peak value in fractional order territory is taken out, then get back to step 3) in circulation operate, until searched for the parameter of target, then the maximal value in each peak value taken out and be stored in a new information matrix A _{1 × N}in.

5) step 2 is repeated) to step 4), until the orientation of total echo data frame has been chosen to cell data and has carried out respective handling;

In step 5) in, owing to thinking that target there will not be the phenomenon of walking about to unit across orientation within the scan period, and and do not know target specifically in which orientation in unit, thus will scan to unit the orientation of Frame, scan each time and all take out the data of the same orientation in each Frame to unit, scanning result carry out step 2) to step 4) operation, and the maximal value that obtains after operation is recorded in information matrix A _{1 × N}in, the first row first row put first time orientation to unit scan and data carry out steps 2) to step 4) and operation after the maximal value that obtains, the maximal value after by that analogy row relax being gone forward side by side to unit scan in all orientation puts into information matrix A successively _{1 × N}in, altogether complete Nth power position to unit scan.

6) maximal value in information matrix is compared, therefrom choose one and be worth most as detection statistic, and carry out CFAR detection in the detecting unit figure be made up of these maximal values.

In step 6) in, need information matrix A _{1 × N}in maximal value take out as detection statistic, in addition by information matrix A _{1 × N}in numerical value composition detecting unit figure in complete transform domain CFAR detection; concrete grammar is around detection statistic, chosen protected location and reference unit; the interference average power content size in transform domain is calculated by reference unit; the adaptive threshold for detecting is obtained according to average power content and false-alarm probability; by detection statistic whether be greater than thresholding to judge target with or without, thus complete detection.

Simulation result and analysis:

The effect of the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order provided by the invention can be further illustrated by following emulation experiment.Simulation parameter is arranged: under space based radar is operated in detection and tracking pattern, the spatial domain of monitoring is divided into 10 orientation to unit, each orientation is to the pulse signal of unit radar emission 64 coherents, receive the echo data of 4 scan periods, the wavelength that transmits is 0.3m, pulse repetition rate is 1500Hz, and signal bandwidth is 30MHz, and carrier frequency is 1GHz.Target component is set to: target is initially at first orientation of the first frame data in unit, speed v ₀=3000m/s, acceleration a ₀=180m/s ².

1, multiframe echo data is scanned, take out echo data, and by the distribution plan after other data zero setting process

Fig. 2 is that the space based radar after separating mediation process of pulse-compression receives data profile.As can be seen from Figure 2, the echo data after separating mediation process of pulse-compression, because target exists larger initial velocity and acceleration, obviously creates across Range cell migration phenomenon, and with range curvature phenomenon.Because backward energy is dispersed in different range units and doppler cells, so be difficult to effectively find target from noise circumstance in low signal-to-noise ratio situation.

2, walk about and echo data distribution plan after range curvature through frequency domain compensation correction distance

Fig. 3 give improved frequency domain compensation correction distance walk about and range curvature after multiframe echo data distribution plan.As can be seen from the figure the echo data after improved frequency domain compensation correction is all corrected in a range gate, and now the range gate at place is only relevant with the initial position of target, thus can provide basis for follow-up process.

3, P _fa=10 ^-4time CFAR detection curve map

Fig. 4 gives at false-alarm probability P _fa=10 ^-4time, each method carries out the curve map after CA-CFAR detection to after the process of multiframe echo data.As can be seen from Figure 4, based on Keystone conversion multiframe coherent TBD method when carrying out Range Walk Correction to echo signal, because target exists larger acceleration, so except range walk, also there will be range curvature phenomenon, and Keystone conversion can only correct once the range walk of item, and the range curvature of quadratic term can not be corrected accordingly, so the energy of target echo signal can not accumulate fully, thus cause can not target be detected in low signal-to-noise ratio situation.Based on the multiframe coherent TBD technology that radial velocity is estimated, equally because echo signal there will be range curvature phenomenon, and during the calculating of radial velocity, do not consider the impact of acceleration, thus make the range walk amount calculated occur comparatively big error, result makes echo signal data can not be displaced to preferably in corresponding range unit, therefore cause and can not accumulate target energy preferably, finally have impact on detection probability.Multiframe coherent TBD technology based on dynamic programming is not in a range unit by target echo Data correction, but pulse signal sampling corresponding for status switch possible for target is put together do correlative accumulation, and its accumulation for noise is far longer than other method, to a certain degree have impact on the detection perform to target.And based on Radon conversion multiframe coherent TBD technology for target range walk about and range curvature in correct very limited, the energy of echoed signal is made still to be dispersed in different range units and doppler cells, thus having had a strong impact on the energy accumulation of target, result reduces the detection perform of target.

4, P _fa=10 ^-6time CFAR detection curve map

Fig. 5 gives at false-alarm probability P _fa=10 ^-6time, each method carries out the curve map after CA-CFAR detection to after the process of multiframe echo data.Conclusion same with Fig. 4 as can be drawn from Figure 5.

Claims (5)

1., based on the multiframe coherent TBD method revising frequency domain compensation and Fourier Transform of Fractional Order, it is characterized in that, described method comprises carries out following step in order:

1) space based radar is received to the maneuvering target echo data obtained and carry out process of pulse-compression in distance frequency domain-slow time domain, then after distance frequency domain does inverse Fourier transform, obtain the range gate after pulse compression-slow time data;

2) from every frame of above-mentioned echo data after pulse compression, select same orientation to the data of unit, other data are carried out zero setting process simultaneously, and will the data of zero setting do not had to process as target echo data;

3) in step 2) on the data basis that obtains, search in the parameter area of target, calculate the frequency domain compensation item revised according to Search Results, correct back to range walk and the range curvature phenomenon of wave datum with frequency domain compensation item;

4) utilize step 3) in obtain through revising the echo data of frequency-domain correction, compensate the phase differential between data in a range unit, then the data having compensated phase differential are carried out Fourier Transform of Fractional Order, peak records in fractional order territory is got off and gets back to step 3) cycling, until target component has been searched for, and the maximal value of a series of peak value is put in new information matrix;

5) step 2 is repeated) to step 4), until the orientation of total echo data frame to be chosen and to carry out respective handling complete to cell data;

6) maximal value in information matrix is compared, therefrom choose one and be worth most as detection statistic, and carry out CFAR detection in the detecting unit figure be made up of these maximal values.

2. the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order according to claim 1, is characterized in that: in step 1) in, described to the method that echo data carries out process of pulse-compression be:

Under space based radar is operated in detection and tracking pattern, the spatial domain of detection is divided into 10 orientation to, utilize frequency matching filtering method to carry out the kth frame after process of pulse-compression to echo data, the maneuvering target echo data form of the n-th localizer unit is:

$s_r(\hat{r},t_m)=A_r^{\′}\sin c\left[\mathrm{\π}\frac{\hat{r}-R\left(t_m\right)}{{\mathrm{\ρ}}_r}\right]\exp (-j\frac{4\mathrm{\π}}{\mathrm{\λ}}{v}_{0t_m})\exp (-j\frac{2\mathrm{\π}}{\mathrm{\λ}}{a}_0{t}_m^2)---\left(1\right)$

In formula (1) the complex magnitude of echo data, t _m=mT _r+ (k-1) NMT _r+ (n-1) MT _rthe slow time, k=1 ..., K represents a kth scan period, n=1 ..., N be orientation in the n-th spatial domain to unit, m=1 ..., M, t'=t-t _mthe fast time, represent the length of range gate, T _rthe indicating impulse repetition time, wherein M represents the umber of pulse in the Coherent processing time, f _crepresent the carrier frequency of signal, for signal wavelength, B _sfor signal bandwidth, r ₀represent the initial distance of target, v ₀represent the initial velocity of target, a ₀represent the acceleration of target, it is the radial distance between target and radar; Be stored in a matrix by the known radar return data of formula (1), the horizontal ordinate of this matrix is slow time t _m, ordinate is respective distances unit the fast time.

3. the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order according to claim 1, it is characterized in that: in step 3) in, described in step 2) on the data basis that obtains, search in the parameter area of target, calculate the frequency domain compensation item revised according to Search Results, the method for the range walk and range curvature phenomenon that correct back to wave datum with frequency domain compensation item is:

Search within the scope of target component, target is calculated for different pieces of information frame and the different azimuth respective correction frequency domain compensation item to unit according to the parameter combinations of each target while search, then echo data is done Fourier transform along distance dimension, distance frequency domain-slow time data can be obtained, then the correction frequency domain compensation item calculated is multiplied by this basis, distance frequency domain f and speed, acceleration and the coupling solutions between the slow time can be removed, reach correction distance and walk about and the object of range curvature phenomenon; Carry out inverse Fourier transform along distance frequency domain afterwards and obtain the range gate after range walk and range curvature correction-slow time domain data.

4. the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order according to claim 1, it is characterized in that: in step 4) in, described utilizes step 3) in obtain through revising the echo data of frequency-domain correction, compensate the phase differential between data in a range unit, then the data having compensated phase differential are carried out Fourier Transform of Fractional Order, peak records in fractional order territory is got off and gets back to step 3) cycling, until target component has been searched for, and the method that the maximal value of a series of peak value is put in new information matrix be:

In step 3) proper phase that basis is brought to unit due to different Frames and orientation between echo data in compensation range unit is poor, the phase place between data is made to meet phase place coherent pulse signalf, then take out the data compensated in a range unit of phase place and carry out Fourier Transform of Fractional Order, after finishing Fourier Transform of Fractional Order, the peak value in fractional order territory is taken out, then step 3 is got back to) recalculate new correction frequency domain compensation item, carry out cycling, until by complete for the range searching of echo data, the maximal value of having searched for the rear peak value obtaining in each fractional order territory is taken out and is put into a new information matrix A successively _{1 × N}in.

5. the multiframe coherent TBD method based on revising frequency domain compensation and Fourier Transform of Fractional Order according to claim 1, it is characterized in that: in step 6) in, described compares the maximal value in information matrix, therefrom choose one to be worth most as detection statistic, and the method for carrying out CFAR detection in the detecting unit figure be made up of these maximal values is:

In step 5) after store the maximal value in the fractional order territory of each orientation to unit scan and after process in the information matrix that obtains; the series of values relatively obtained; most value is wherein taken out as detection statistic; then around detection statistic, protected location and reference unit is selected; thus determine adaptive threshold according to the CA-CFAR check processing method in transform domain; by detection statistic whether cross thresholding judge target with or without, complete detection.